LeeChuanjing

Tile & Floor Calculator

Estimate tiles, boxes and cost for kitchens, bathrooms and whole floors - with diagonal-pattern waste built in.

How the tile estimate works

The calculator converts your tile size from inches to feet (divide by 12), multiplies length by width to get the area of one tile, then divides the room area (with a waste allowance) by that number. It rounds up to whole tiles and groups them into boxes.

Tile area = (tileL / 12) x (tileW / 12) sq ft
Tiles = (roomL x roomW x (1 + waste%)) / tile area, rounded up
Boxes = ceil(tiles / tilesPerBox)

Choosing a realistic waste percentage

A straight grid in a rectangular room loses little to cuts, so 10% is safe. Diagonal layouts, hexagonal or chevron patterns, and oversized slabs waste far more because nearly every edge is a cut - plan for 15-20%. If your room has many inside corners, add another 5%.

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Use cases

  • Kitchen backsplash - small area, but many cuts around outlets; bump waste to 15%.
  • Bathroom floor - subtract the vanity and toilet footprint if you will not tile under them.
  • Whole-house flooring - tile each room, then sum boxes to qualify for contractor or bulk pricing.
  • Feature wall - vertical tiling uses the same math; just treat wall height x width as the "floor".

Tiles per square foot cheat sheet

A 12 x 12 inch tile is exactly 1 sq ft. An 18 x 18 is 2.25 sq ft (about 0.44 tiles per sq ft). A 24 x 24 is 4 sq ft (0.25 tiles per sq ft). Larger formats mean fewer grout lines but more cutting waste, so the waste factor matters more, not less.

Frequently asked questions

How much extra tile should I buy?
A 10% waste allowance covers straight layouts in a rectangular room. For diagonal patterns, hexagonal or large-format tiles, increase to 15-20% because more cuts are wasted.
How do I calculate tiles per square foot?
Convert the tile size to feet (inches divided by 12), multiply length by width to get square feet per tile, then divide 1 by that number. A 12x12 inch tile is 1 sq ft, so 1 tile per sq ft.
Why buy whole boxes?
Tiles are dyed in batches. Buying full boxes from one batch avoids visible shade differences. Leftover unopened boxes can usually be returned.
Estimates only. Pattern complexity, substrate shape and breakage vary. Confirm quantities with your tile retailer.

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Calculating tile with waste factor built in

How to use this calculator

  1. Measure the length and width of each wall or floor area in feet and multiply for square footage.
  2. Subtract nothing for doors and windows under about 15 square feet — the offcuts around them absorb the savings.
  3. Add a waste factor: 10% for straight-lay layouts with standard tiles, 15–20% for diagonal patterns, herringbone, or large-format tiles.
  4. Divide the total by the coverage of one tile (its length × width in square feet) to get the tile count, then round up to the nearest full box.
  5. Buy all tile for a project from the same lot — dye-lot variation between batches is visible once installed.

Quick reference

Layout Waste factor Why
Straight lay (grid)10%Simple cuts, predictable offcuts
Brick / offset10–15%More edge cuts at joints
Diagonal (45°)15%Every border tile is a cut
Herringbone15–20%Many angle cuts per tile
Large-format tile15%Fewer pieces per box; one break hurts more
Pro tips
  • Grout line width slightly changes tile count in large rooms — 1/8-inch versus 1/4-inch lines can shift total coverage by a few percent.
  • Keep at least one full box of each tile after the job for future repairs; a cracked tile years later is easier to fix with an exact match.
  • Backer board, waterproofing membrane, and thinset are separate line items — tile calculators do not include them.

Frequently asked questions

How much extra tile should I buy?

A 10% waste factor suits straightforward floors and walls; use 15–20% for diagonal, herringbone, or patterned layouts, and whenever tiles are brittle or sold in small boxes.

Can I mix tiles from different boxes?

Check the shade and calibre codes printed on the box. Tiles from different production lots can differ subtly in color and size, so mix from multiple boxes of the same lot during installation to blend any variation.

Does grout color change how much tile I need?

No — grout fills the joints between tiles; it does not change the tile count. It does change how the finished floor reads visually, with darker grout hiding stains and lighter grout making rooms feel larger.